An uninterruptible power supply (UPS) is an electrical apparatus that provides emergency power to a load when the input power source, typically the utility mains, fails. A UPS differs from an auxiliary or emergency power system or standby generator in that it will provide instantaneous or near-instantaneous protection from input power interruptions by means of one or more attached batteries and associated electronic circuitry. While not limited to protecting any particular type of equipment, a UPS is often used to protect computers, data centers, telecommunication equipment and other electrical equipment where an unexpected power disruption could cause injuries, fatalities, serious business disruption or data loss.
An inverter is an electrical device that converts direct current (DC) to alternating current (AC). The converted AC can be established at any desired voltage and frequency with the use of appropriate transformers, switching, and control circuits. Solid-state inverters have no moving parts and are used in a wide range of applications, from small switching power supplies in computers to large electric utility high-voltage direct current applications that transport bulk power. Inverters are commonly used to supply AC power to loads from DC power sources.
A battery charger is a device that is used to transfer energy into a secondary cell or a rechargeable battery by forcing an electric current through it. In some cases battery chargers are designed for high-efficiency conversion of incoming commercial AC mains power to DC power for charging large banks of station batteries, while supplying power to continuous DC loads such as inverters. Such battery chargers are often used in conjunction with UPS systems, as well as a standalone device for battery charging only applications.
Due their criticality, there is a continuing need to increase the efficiency and reliability of UPS systems, inverters and battery chargers.